The online contest was held on hackerrank platform. The test was same for all the IITs and was conducted at the exact date and time in all the campuses. There were three sections – CS (5 MCQ and 2 coding questions), Quant (10 MCQs) and ML (10 MCQs) . Each MCQ carried +3 for correct answer and -1 for incorrect answer. The test duration was 2hrs 30 mins with CS and Quant of an hour each and ML of 30 minutes. We could easily switch between the sections and the timer for each section would continue from where we had left off. The ML section wasn’t really ML, it was more of statistics stuff. The strategy should be to sacrifice a section and utilize its time to solve questions from other sections. You need not perform well in all 3 sections. Try to master 2 sections to gain a good score(The interviewers maintain a score secured in each round together with the performance in the online test to select the best candidate for their firm. Hence performance in each round is crucial).
Around 80 students were shortlisted out of 500.
Interview Round 1:
I had performed exceptionally well in the online test. Hence the questions asked in this round were easy. They asked me only two questions:
- Reverse a linked list (not just the function).
- Given two unsorted arrays, find the median(not the brute force approach).
The interviewers were very smart and wanted to know how each step of the program I had written actually worked.
Interview Round 2:
The interviewer told me that this round would test my logical skills. He started straight with the questions. I had prepared myself for the puzzles but the questions asked in this round didn’t look familiar to me.
- Given a chessboard with a property that the number on each cell was equal to average of all the numbers on its surrounding cells. A number on a random cell was given and I had to find the number on top right corner cell. After I gave my solution he told me to prove how I arrived at that solution.
- The second question was also on proof. I don’t remember the question clearly but it was on a 9×9 matrix which satisfied certain properties and he asked me to prove something. The solution was to prove by contradiction. This was a very difficult question.
- He asked me about the various distributions I knew. He asked me all about normal distribution and its properties. He also asked me about expectation. He then gave me a problem to calculate the expectation of a function with its random variable being a normal distribution. Basically the problem was to solve the integration without solving it ,i.e. just by observing without doing any math stuff. The idea was to draw the graph for the given function and deduce that it was symmetrical about the y axis and hence could be solved without doing any mathematical steps of integration.
- He asked me about independent random variables and their expectation. Then he asked me to prove that E(X) >= E(sq. root X)^2
- He asked me about uniform distribution and gave a question on it. Given 3 random variables X,Y,Z each with uniform distribution between (0,1). X forms sides of a square while Y and Z forms sides of a rectangle. Calculate the expected areas of the square and rectangle and which one would be greater.
The interviewer was really impressed with me after this round.
Interview Round 3:
He straightaway started with the questions:
- Given n vertical line segments(2 coordinate points for each line segment,i.e 2*n points) parallel to the y axis, find if there exists a straight line of any slope which passes through all the given line segments. I found this very difficult to solve.
- Given n lines such that none are parallel and there are nC2 intersection points,find the number of intersection points to the right of y axis and do this in most optimized time complexity.
- Given n docks on 2 sides of the river each with its corresponding number on it. Calculate maximum number of ships that can move from one dock to its corresponding dock on the other side without crossing over other ships.(Variation of LIS)
- We have nxn matrix and we need to find any one row such that it contains neither the maximum nor the minimum of all the n^2 elements in O(n) time complexity.
16 people were hired and I was one of them.
P.S. : You need to be very attentive and listen to everything very carefully as there lies hints in the way they ask the questions and you need to be smart enough to identify all the hints.
Only 3 among top 10(from online test) were selected, so don’t take anything for granted. Also people who were ranked even as high as 60 in the online test were hired. The myth about GS that only top 30 are given preference was completely shattered.